To test if it works edit your ~/.xinitrc as user, comment the exec xterm part out and add exec startxfce4.

Since Xfce doesnt have its own display manager for a graphical login so you have to install one yourself. You could either install xdm, kdm or gdm. Gdm is the GNOME display manager and also uses the GTK+ toolkit so it's a good choice for Xfce, too.